Systematic Review: Attention-Deficit/Hyperactivity Disorder and Instrumental Learning

Novel and complementary treatment approaches in attention-deficit/hyperactivity disorder

PURPOSE OF REVIEW

To provide an updated review of novel and complementary treatment approaches for children and adolescents with attention-deficit/hyperactivity disorder.

RECENT FINDINGS

The evidence for complementary attention-deficit/hyperactivity disorder treatments is often promising, but limited to small, unblinded studies. Recent evidence from larger, more rigorous studies reveals that most of these treatments have modest efficacy. Omega-3 polyunsaturated fatty acids, saffron, broad spectrum micronutrients, and physical exercise have potential benefits that seem to outweigh known risks. However, neurofeedback, cognitive training, and trigeminal nerve stimulation need further research to determine whether specific sub-groups of children/adolescents with attention-deficit/hyperactivity disorder would benefit long-term with their associated tolerable risks.

SUMMARY

There is not sufficient evidence for complementary treatments to be recommended as substitutes for first-line pharmacological and psychosocial treatment options. Nonetheless, some adjuvant therapies to currently recommended attention-deficit/hyperactivity disorder treatments can be safe. Physicians should be familiar with existing and emerging complementary treatments to help guide families.

Behavioral and Emotional Responding to Punishment in ADHD: Is Increased Emotionality Related to Altered Behavioral Responding?

Children with ADHD are theorized to experience increased negative emotional responses to punishment, compared to typically developing (TD) children, resulting in altered behavioral responding (Amsel, 1992). However, this has not been empirically tested. The current study evaluated the effects of punishment and reward on the behavioral and emotional responding of children with and without ADHD. Fifty-three children with ADHD (64.15% boys) and 46 TD children (47.83% boys), age 6-12, completed a task in which they chose between playing two simultaneously available games. Reward was arranged symmetrically across the games; responses on one game were punished four times as often as responses on the other game. Children's negative and positive emotional expressions were assessed during task completion with facial expression coding. Results indicated both groups showed a preference for playing the less punished game. Children with ADHD took longer to respond after punishment and reward compared to TD children. Negative emotional expressions increased with time on task for those with ADHD, the opposite pattern was seen in TD children. Children with ADHD showed more positive emotional expressions overall. The effect of ADHD on increased response times after reward was statistically fully mediated by increased positive facial expressions. Findings indicate children with ADHD do not show an altered response bias under punishment compared to TD children, but their cumulative negative emotional responding may indicate problems with building frustration tolerance as hypothesized by Amsel (1992). Results are theoretically important as they suggest increased emotional responding in ADHD is associated with slower responding.

Assessing Inhibitory Control Deficits in Adult ADHD: A Systematic Review and Meta-analysis of the Stop-signal Task

In recent years, there has been an increasing quest in improving our understanding of the neurocognitive deficits underlying adult attention-deficit/hyperactivity disorder (ADHD). Current statistical manuals of psychiatric disorders emphasize inattention and hyperactivity-impulsivity symptoms, but empirical studies have also shown consistent alterations in inhibitory control. To date, there is no established neuropsychological test to assess inhibitory control deficits in adult ADHD. A common paradigm for assessing response inhibition is the stop-signal task (SST). Following PRISMA-selection criteria, our systematic review and meta-analysis integrated the findings of 26 publications with 27 studies examining the SST in adult ADHD. The meta-analysis, which included 883 patients with adult ADHD and 916 control participants, revealed reliable inhibitory control deficits, as expressed in prolonged SST response times, with a moderate effect size g = 0.51 (95% CI: 0.376-0.644, p < 0.0001). The deficits were not moderated by study quality, sample characteristics or clinical parameters, suggesting that they may be a phenotype in this disorder. The analyses of secondary outcome measures revealed greater SST omission errors and reduced go accuracy in patients, indicative of altered sustained attention. However, only few (N < 10) studies were available for these measures. Our meta-analysis suggests that the SST, in conjunction with other tests and questionnaires, could become a valuable tool for assessing inhibitory control deficits in adult ADHD.

Novel pharmacological targets for GABAergic dysfunction in ADHD

Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopment disorder that affects approximately 5% of the population. The disorder is characterized by impulsivity, hyperactivity, and deficits in attention and cognition, although symptoms vary across patients due to the heterogenous and polygenic nature of the disorder. Stimulant medications are the standard of care treatment for ADHD patients, and their effectiveness has led to the dopaminergic hypothesis of ADHD in which deficits in dopaminergic signaling, especially in cortical brain regions, mechanistically underly ADHD pathophysiology. Despite their effectiveness in many individuals, almost one-third of patients do not respond to stimulant treatments and the long-term negative side effects of these medications remain unclear. Emerging clinical evidence is beginning to highlight an important role of dysregulated excitatory/inhibitory (E/I) balance in ADHD. These deficits in E/I balance are related to functional abnormalities in glutamate and Gamma-Aminobutyric Acid (GABA) signaling in the brain, with increasing emphasis placed on GABAergic interneurons driving specific aspects of ADHD pathophysiology. Recent genome-wide association studies (GWAS) have also highlighted how genes associated with GABA function are mutated in human populations with ADHD, resulting in the generation of several new genetic mouse models of ADHD. This review will discuss how GABAergic dysfunction underlies ADHD pathophysiology, and how specific receptors/proteins related to GABAergic interneuron dysfunction may be pharmacologically targeted to treat ADHD in subpopulations with specific comorbidities and symptom domains. This article is part of the Special Issue on "PFC circuit function in psychiatric disease and relevant models".

Predictors of Health-Related Quality of Life in Neurodivergent Children: A Systematic Review

Health-related Quality of Life (HRQoL) is a multi-faceted construct influenced by a myriad of environmental, demographic, and individual characteristics. Our understanding of these influencers remains highly limited in neurodevelopmental conditions. Existing research in this area is sparse, highly siloed by diagnosis labels, and focused on symptoms. This review synthesized the evidence in this area using a multi-dimensional model of HRQoL and trans-diagnostically across neurodevelopmental conditions. The systematic review, conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Checklist, was completed in June 2023 using Medline, PsycInfo, Embase, PubMed, and Cochrane Library. Our search revealed 78 studies that examined predictors of HRQoL in neurodevelopmental conditions. The majority of these studies focused on autism and ADHD with a paucity of literature in other conditions. Cross-diagnosis investigations were limited despite the fact that many of the examined predictors transcend diagnostic boundaries. Significant gaps were revealed in domains of biology/physiology, functioning, health perceptions, and environmental factors. Very preliminary evidence suggested potentially shared predictors of HRQoL across conditions including positive associations between HRQoL and adaptive functioning, male sex/gender, positive self-perception, physical activity, resources, and positive family context, and negative associations with diagnostic features and mental health symptoms. Studies of transdiagnostic predictors across neurodevelopmental conditions are critically needed to enable care models that address shared needs of neurodivergent individuals beyond diagnostic boundaries. Further understanding of HRQoL from the perspective of neurodivergent communities is a critical area of future work.

Exploring the steps of learning: computational modeling of initiatory-actions among individuals with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is characterized by difficulty in acting in a goal-directed manner. While most environments require a sequence of actions for goal attainment, ADHD was never studied in the context of value-based sequence learning. Here, we made use of current advancements in hierarchical reinforcement-learning algorithms to track the internal value and choice policy of individuals with ADHD performing a three-stage sequence learning task. Specifically, 54 participants (28 ADHD, 26 controls) completed a value-based reinforcement-learning task that allowed us to estimate internal action values for each trial and stage using computational modeling. We found attenuated sensitivity to action values in ADHD compared to controls, both in choice and reaction-time variability estimates. Remarkably, this was found only for first-stage actions (i.e., initiatory actions), while for actions performed just before outcome delivery the two groups were strikingly indistinguishable. These results suggest a difficulty in following value estimation for initiatory actions in ADHD.

A systematic meta-review of systematic reviews on attention deficit hyperactivity disorder

BACKGROUND

There are now hundreds of systematic reviews on attention deficit hyperactivity disorder (ADHD) of variable quality. To help navigate this literature, we have reviewed systematic reviews on any topic on ADHD.

METHODS

We searched MEDLINE, PubMed, PsycINFO, Cochrane Library, and Web of Science and performed quality assessment according to the Joanna Briggs Institute Manual for Evidence Synthesis. A total of 231 systematic reviews and meta-analyses met the eligibility criteria.

RESULTS

The prevalence of ADHD was 7.2% for children and adolescents and 2.5% for adults, though with major uncertainty due to methodological variation in the existing literature. There is evidence for both biological and social risk factors for ADHD, but this evidence is mostly correlational rather than causal due to confounding and reverse causality. There is strong evidence for the efficacy of pharmacological treatment on symptom reduction in the short-term, particularly for stimulants. However, there is limited evidence for the efficacy of pharmacotherapy in mitigating adverse life trajectories such as educational attainment, employment, substance abuse, injuries, suicides, crime, and comorbid mental and somatic conditions. Pharmacotherapy is linked with side effects like disturbed sleep, reduced appetite, and increased blood pressure, but less is known about potential adverse effects after long-term use. Evidence of the efficacy of nonpharmacological treatments is mixed.

CONCLUSIONS

Despite hundreds of systematic reviews on ADHD, key questions are still unanswered. Evidence gaps remain as to a more accurate prevalence of ADHD, whether documented risk factors are causal, the efficacy of nonpharmacological treatments on any outcomes, and pharmacotherapy in mitigating the adverse outcomes associated with ADHD.

Instrumental learning and behavioral persistence in children with attention-deficit/hyperactivity-disorder: does reinforcement frequency matter?

BACKGROUND

Prominent theoretical accounts of attention-deficit/hyperactivity-disorder (ADHD) hypothesize that reinforcement learning deficits underlie symptoms of ADHD. The Dynamic Developmental Theory and the Dopamine Transfer Deficit hypothesis assume impairments in both the acquisition and extinction of behavior, especially when learning occurs under partial (non-continuous) reinforcement, and subsequently the Partial Reinforcement Extinction Effect (PREE). Few studies have evaluated instrumental learning in ADHD and the results are inconsistent. The current study investigates instrumental learning under partial and continuous reinforcement schedules and subsequent behavioral persistence when reinforcement is withheld (extinction) in children with and without ADHD.

METHODS

Large well-defined samples of children with ADHD (n = 93) and typically developing (TD) children (n = 73) completed a simple instrumental learning task. The children completed acquisition under continuous (100%) or partial (20%) reinforcement, followed by a 4-min extinction phase. Two-way (diagnosis by condition) ANOVAs evaluated responses needed to reach the learning criterion during acquisition, and target and total responses during extinction.

RESULTS

Children with ADHD required more trials to reach criterion compared to TD children under both continuous and partial reinforcement. After partial reinforcement, children with ADHD executed fewer target responses during extinction than TD children. Children with ADHD executed more responses than TD children during extinction, irrespective of learning condition.

CONCLUSIONS

The findings demonstrate general difficulties in instrumental learning in ADHD, that is, slower learning irrespective of reinforcement schedule. They also show faster extinction following learning under partial reinforcement in those with ADHD, that is, a diminished PREE. Children with ADHD executed more responses during extinction. Results are theoretically important, with clinical implications for understanding and managing learning difficulties in those with ADHD, as they suggest poorer reinforcement learning and lower behavioral persistence.

Poor learning or hyper-exploration?: A commentary on Hulsbosch et al. (2023)

In an outstanding paper, Hulsbosch et al. (Journal of Child Psychology and Psychiatry, 2023) tested major reinforcement learning theories of attention-deficit/hyperactivity disorder (ADHD). On a reinforcement learning task, children with ADHD needed more trials to reach the criterion in the learning phase and chose the target less often in the extinction phase. These results only partially support either of the theories and may be interpreted as reflecting a general deficit in learning. Still, distinguishing between learning and decision-making stages suggests that poor performance on reinforcement learning tasks by children with ADHD is accounted for by increased exploration or decreased choice consistency rather than deficient learning.

The impact of ADHD symptom severity on reinforcement and punishment learning among adults

Introduction: Aberrations in feedback learning are hypothesised to contribute to the behavioural disruptions and impairment of attention-deficit/hyperactivity disorder (ADHD). However, few studies have evaluated the relation of reward/punishment feedback and ADHD symptom severity on learning. The current study evaluates the differential effects of reward and punishment feedback on learning among adults with elevated ADHD. Methods: One hundred five participants self-reported their level of current ADHD symptoms and completed an innovative instrumental learning task. Results: Consistent with predictions, participants with low self-reported ADHD symptom severity benefitted equally from reward and punishment feedback during the learning task, whereas participants with high self-reported symptom severity performed better (indexed by accuracy on learning task) from reward than punishment feedback trials. Conclusions: Overall, adults with high self-reported symptom severity of ADHD learned more from reward-based feedback, which provides critical implications for motivational theories about ADHD, as well as for treatment protocols. Future work should examine the translatability of results within a treatment setting.

Understanding Problematic Social Media Use in Adolescents with Attention-Deficit/Hyperactivity Disorder (ADHD): A Narrative Review and Clinical Recommendations

Attention-Deficit/Hyperactivity Disorder (ADHD) is consistently associated with a host of social problems, such as victimization and difficulties in maintaining close friendships. These problems are not limited to offline relations but also manifest in the online social world, as previous research shows that ADHD is associated with problematic use of social media. Given the ubiquitous nature of social media, the goal of the current review is to understand why adolescents with ADHD demonstrate more problematic social media use than their typically developing peers. To this end, we provide a narrative review on the evidence for the link between ADHD and social media use, and consequently present an integrative framework, which encompasses neurobiological mechanisms (i.e., imbalance theory of brain development and dual pathway model of ADHD) and social mechanisms, including influences from peers and parents. We conclude that empirical work shows most consistent evidence for the link between problematic social media use and ADHD (symptoms), while intensity of social media use is also associated with several other behaviors and outcomes. Finally, we hypothesize how existing interventions for ADHD may work on the identified mechanisms and provide at-hand clinical recommendations for therapists working with adolescents with ADHD who exhibit problematic social media use.

Editorial: Instrumental Learning in Children With Attention-Deficit/Hyperactivity Disorder: A Rewarding Review Incentivizing Future Research

The mechanisms underlying attention-deficit/hyperactivity disorder (ADHD) continue to elude researchers, hindering efforts to improve diagnosis and treatment of the disorder.¹ Notably, mechanisms such as operant conditioning, or instrumental learning, have been surprisingly underemphasized in the ADHD literature. This is curious given that behavioral interventions, which rely on the principles of operant conditioning, are one of only a few well-established interventions for ADHD.² In this issue of the Journal, Hulsbosch et al.³ sought to answer critical questions regarding instrumental learning in children with ADHD through a systematic review that updates and extends prior reviews.⁴.